The present invention involves the art of connecting and clamping together adjoining lengths of flanged pipes, tubes and ducts, hereafter generally referred to as "ducts". Such connections are commonly employed in a variety of hydraulic and pneumatic systems. The system disclosed herein is particularly well suited for applications where an assured seal is essential, notwithstanding large pressure differentials between the duct interior and exterior, and where preliminary adjustment of the relative angular position of the adjoining ducts about their common axis is desired, even after an initial connection of the ducts.
Duct ends have in the past been commonly formed with peripheral flanges having conical surfaces which taper outwardly toward the end of the duct. O-rings or gaskets have been employed between the abutting flanges of the ducts to be joined, so that when a V-type retainer ring is tightened around the joined ducts, the flanges are wedged toward each other to compress the seal.
An example of this type of prior art connection is the V-retainer coupling manufactured by Voss Industries, Inc. of Cleveland, Ohio. This coupling generally consists of a ring having a V-shaped cross-section, with the legs of the V engaging the conical surfaces of the duct flanges, the V-ring being supplemented by an additional flat band secured to the outer circumference of the ring, that is, to the base of the V-shaped portion. A threaded connection at the ends of the coupling draws the ends together to establish the clamping force. The coupling is fabricated of metal, and the side walls or legs of the V-shaped portion must therefore be interrupted at one or more points around the perimeter to permit the ring to be spread apart during assembly over the duct flanges without buckling or tearing of these legs. This interruption in the continuity of the clamping ring reduces the effectiveness of the clamping pressure against the sealing means in the area of the gap.
It is an object of the present invention to provide an improved clamping system for flanged ducts which provides an effective and continuous seal around the full periphery of the duct joint, and which provides multiple stages or lines of sealing engagement. It is a further object to provide such a clamping system which can be initially positioned over the adjoining ducts to maintain the ducts in their joined condition prior to final clamping while permitting the ducts to be rotated about their common axis to a desired angular position.
The above objects have been accomplished by the present invention by the creation of a clamping ring which may be injection molded from a plastic material such as polyurethane, pheyelene oxide, polyphenylene sulfide, or polyterafluoroethylene (such as "Halon", "Teflon" or "Fluon"). The clamping ring is formed with a relatively soft compressible seal which is either molded in place or bonded to the full inner perimeter of the ring and positioned to engage the outer rim of the duct flanges and, in an alternative embodiment, to additionally engage the conical surfaces of the duct flanges.
One end of the clamping ring is additionally provided with an undercut recess which receives a projection from the other end to establish a temporary latching position. The seal is turned radially outwardly in such recess and is positioned to be abutted and compressed by the latching projection, to establish a complete uninterrupted seal around the full periphery of the joint.